Mary Tudor married her first cousin, Philip II of Spain. William III and Mary II were also first cousins. Neither marriage produced children.
Albert Einstein’s second wife was his first cousin on maternal side(mothers were sisters) and 2nd cousins on fathers’ sides (fathers were first cousins). No children from that marriage.
Albert Einstein’s second wife was his first cousin on maternal side(mothers were sisters) and 2nd cousins on fathers’ sides (fathers were first cousins). No children from that marriage.
The end result is Charles II of Spain:
Charles’ reign has traditionally been viewed as one of decline and decay, a foreign ambassador commenting in 1691 “it is incomprehensible how this monarchy survives”.
https://en.wikipedia.org/wiki/Charles_II_of_Spain#Legacy